A service area of a wireless telecommunications network is typically broken up into contiguous geographic regions called cells. In 4G networks, commonly known a long term evolution (LTE) networks, each cell is associated with an eNodeB (eNB), or base station and each cell is assigned to a tracking area. A cell is associated with a specific geographic service area and multiple cells can be associated with a specific tracking area. Also, an eNodeB may be associated with more than one cell. Consequently, a tracking area covers a geographic service area made up of the set of cells that are assigned to that tracking area. A mobility management entity (MME), similarly to an MSC in a 3G network, is responsible for managing the communications of UEs through a plurality of eNBs in one or more tracking areas.
As each UE moves through a geographic area, it transmits a tracking are update (TAU) request when it detects that it has entered a tracking area where it is not registered. The MME associated with the tracking area receives the TAU requests and maintains a record with information associated with the UE. When the MME receives a request to connect with a registered UE, the MME sends out a paging request to alert the UE that a connection is desired.
LTE providers have found that they need to increase the size of tracking areas in order to reduce the frequency of TAU procedures. In other words, if UEs change their tracking area less often, fewer TAU procedures will be using communication bandwidth. Unfortunately, while this increase in the size of tracking areas reduces the number of TAU procedures performed, it significantly increases the amount of paging traffic that must be handled by each eNodeB for connecting with individual UEs. Typically, the last seen eNodeB is part of the information the MME maintains for each UE and when a request to connect is received, the MME initially sends a paging request to this eNodeB. If the paging request fails, however, the MME then sends a paging request to all the eNodeBs within the same tracking area as the last seen eNodeB. If this paging request fails, a paging request can be sent out to all the eNBs in the same tracking area as well as one or more neighboring tracking areas. As the size of tracking areas increases, they encompass more eNodeBs and each eNodeB receives more paging requests.
Thus, a need exists for to support paging of more than a single eNodeB but less than a full Tracking Area. There is also a need to select a subset of eNodeBs to be paged where the UE is most likely to be present. The need for efficient paging is especially acute with regard to voice over internet protocol (VoIP) calls where a call will go to voice mail if a paging request isn't answered in a given amount of time.